I’d focus more on print usability and readability guidelines than computer guidelines. 5Hz eink is closer to a moving newspaper than a slow computer.

https://www.mediapoint.com.au/design-tips/composition-layout... might be moderately helpful.

But my advice: do not count on anything refreshing ever. Do not have animations, or transitions. Preload things to the correct spaces, then fill in. Reserve fixed white areas for output, and then fill in with black. (This works much better than the reverse!)

For quite long running processes, it might be worth having it behind a second page load.